Re: [PATCH 1/7] PM / OPP: Introduce a power estimation helper
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: 2019-01-29 05:10:37
Also in:
linux-arm-kernel, linux-pm, lkml
On 28-01-19, 16:55, Quentin Perret wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/opp/of.c b/drivers/opp/of.c index 06f0f632ec47..7572a2eb2fd4 100644 --- a/drivers/opp/of.c +++ b/drivers/opp/of.c@@ -1047,3 +1047,63 @@ struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp) return of_node_get(opp->np); } EXPORT_SYMBOL_GPL(dev_pm_opp_get_of_node); + +/** + * of_dev_pm_opp_get_cpu_power() - Estimates the power of a CPU + * @mW: pointer to the power estimate in milli-watts + * @KHz: pointer to the OPP's frequency, in kilo-hertz + * @cpu: CPU for which power needs to be estimated + * + * Computes the power estimated by @CPU at the first OPP above @KHz (ceil), + * and updates @KHz and @mW accordingly. + * + * The power is estimated as P = C * V^2 * f, with C the CPU's capacitance + * (read from the 'dynamic-power-coefficient' devicetree binding) and V and f + * respectively the voltage and frequency of the OPP. + * + * Return: -ENODEV if the CPU device cannot be found, -EINVAL if the power + * calculation failed because of missing parameters, 0 otherwise. + */ +int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu)
I would suggest to change the return type to unsigned long and return 0 for errors and positive values for mW.
+{
+ unsigned long mV, Hz, MHz;MHz is used only once, I think you can get rid of it just open code the division by 1000000. Maybe remove Hz as well and directly use kHz.
+ struct device *cpu_dev; + struct dev_pm_opp *opp; + struct device_node *np; + u32 cap; + u64 tmp;
Name this mW with the above changes.
quoted hunk ↗ jump to hunk
+ int ret; + + cpu_dev = get_cpu_device(cpu); + if (!cpu_dev) + return -ENODEV; + + np = of_node_get(cpu_dev->of_node); + if (!np) + return -EINVAL; + + ret = of_property_read_u32(np, "dynamic-power-coefficient", &cap); + of_node_put(np); + if (ret) + return -EINVAL; + + Hz = *KHz * 1000; + opp = dev_pm_opp_find_freq_ceil(cpu_dev, &Hz); + if (IS_ERR(opp)) + return -EINVAL; + + mV = dev_pm_opp_get_voltage(opp) / 1000; + dev_pm_opp_put(opp); + if (!mV) + return -EINVAL; + + MHz = Hz / 1000000; + tmp = (u64)cap * mV * mV * MHz; + do_div(tmp, 1000000000); + + *mW = (unsigned long)tmp; + *KHz = Hz / 1000; + + return 0; +} +EXPORT_SYMBOL_GPL(of_dev_pm_opp_get_cpu_power);diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h index 0a2a88e5a383..fedde14f5187 100644 --- a/include/linux/pm_opp.h +++ b/include/linux/pm_opp.h@@ -322,6 +322,7 @@ int dev_pm_opp_of_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpuma struct device_node *dev_pm_opp_of_get_opp_desc_node(struct device *dev); struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp); int of_get_required_opp_performance_state(struct device_node *np, int index); +int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu); #else static inline int dev_pm_opp_of_add_table(struct device *dev) {@@ -364,6 +365,10 @@ static inline int of_get_required_opp_performance_state(struct device_node *np, { return -ENOTSUPP; }
Add a blank line here. We missed adding the same before of_get_required_opp_performance_state() earlier, maybe add the new routine before of_get_required_opp_performance_state() and add blank line before and after it :)
+static inline int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu)
+{
+ return -ENOTSUPP;
+}
#endif
#endif /* __LINUX_OPP_H__ */
--
2.20.1-- viresh